Ups and downs in the sales industry are normal, but a decrease of this magnitude is not.

At the start of the month, Nissan announced its U.S. vehicle sales for the month of April were 78,804. This volume is a 29.1 percent drop from the brand's April 2017 sales, in which Nissan moved 111,201 vehicles. And it's a 45.7 percent dive from its March 2018 sales, which were 145,103. As a result, Nissan has had its worst month of sales since September 2013, when it reported 77,828 vehicles sold.

A large portion of the drop can be accounted for by dipping Altima sales. The Altima is down 48.7 percent, with almost 10,000 more sold in April of last year. The Sentra and Maxima suffered too, each selling thousands fewer than this same period in 2017, but their percentage drops differ broadly. Sentra sales were down 16.1 percent from 2017's year-over-year tally, though the car's year-to-date sales are up 7.4 percent from last year's running total. The Maxima's 62.3 percent tumble from 5,564 sold in April 2017 to 2,100 sold in 2018, marks one of the bigger drops but not quite the largest.

Dropping the farthest is the Nissan Juke, which was already struggling this time last year, selling 986 vehicles in April 2017. It sold just 83 year-over-year, a staggering 91.6 percent drop. Presumably, buyers are holding out for the Juke's successor, the Kicks, due later this year at a lower price than the Juke. Nissan's other crossover and SUV offerings also fared poorly, despite a market paradigm shift toward the body style.

Looking back at last year's figures, the Titan pickup is down 33.8 percent in 2018, and its Armada derivative 14.6 percent. The Rogue, Murano, and Pathfinder all endured equally serious sales slowdowns year-over-year, to the tune of 14.8, 38.4, and 52 percent respectively.

Nissan's aging enthusiast car options, which include the 370Z (which will turn nine this year) and the GT-R, both lost around a third of their already low sales volume from 2017 to 2018. There were 260 370Zs sold in April 2018, and 35 GT-Rs.

The Drive reached out to Nissan about why the company thinks its sales have seen such a serious downturn and will update if we hear back.